Robert Louis Stevenson's yarn of the troubled scientist and his sinister alter ego have been the basis for countless updatings and reimaginings, but few have been as successful as "Jekyll," the BBC's recent series that works both on its own and as a clever sequel of sorts to the original novel. It's one of the most inventive attempts at modernizing a classic ever seen on screens large or small.

The series is nearly flawless all around, from airtight direction to crisp production values, but it's the combination of Steven Moffat's brilliant script and a knockout cast led by James Nesbitt that leads "Jekyll" to become unforgettable viewing. Moffat, best known for his hit sitcom "Coupling," showed off his genre chops as the author of some of the smartest episodes from the new "Doctor Who;" with "Jekyll," he turns in arguably his finest work to date, a twisty, twisted thriller that places character first. Add to this, then, a praiseworthy ensemble cast (which also includes Gina Bellman, Denis Lawson, Michelle Ryan, Meera Syal, and Fenella Woolgar), and you have a series that never stops engaging the viewer.

We open with Dr. Tom Jackman (Nesbitt) locking himself into restraints as he warned his newly hired assistant (Ryan) that his condition is a bit more severe than the usual split-personality disorder. He also explains that he's worked out a set of rules with his mysterious other self: a GPS locating device must be worn at all times, set in sync with a digital voice recorder, which will give Dr. Jackman an account of his other half's whereabouts at all times. Other agreements are more practical: Dr. Jackman lets his other half be, or else the other half will simply kill them both; the other half won't kill anyone else, or else Dr. Jackman will turn himself in to the police.

But it's even more complicated. Dr. Jackman is married - albeit none too happily, considering he's abandoned his family without so much as a note - but he's pretty sure his second self doesn't know anything about it. In fact, the other half doesn't even know Dr. Jackman's name. Such are the privacies that become part of this "body share." Which makes the other half look like a sensible person, which is certainly not the case, considering Dr. Jackman's noticeable fear.

It's a very long time before we ever meet the second self, who is later dubbed "Mr. Hyde" by an unseen somebody out of a perverse connection to the old story. Until then, we witness everything through Jackman's point of view alone. His blackouts leave gaping holes in his own timeline, and as he struggles to piece together Hyde's actions, we work on the mystery, too. We follow Jackman's frustrations and learn just how one man can try to outwit himself (both use a rule - recorders can be turned off if you're staying in one place for hours - to hide important facts from the other).

When Hyde is finally revealed, around the 23-minute mark, it's a familiar situation, with Jackman being harassed by a street hood, tensions mounting. Surely we know that Hyde is on his way, but watch how Moffat and director Douglas Mackinnon build that pressure. They make Hyde's arrival a waiting game, tossing us just a little more and a little more as the seconds tick by, until, at long last, Nesbitt turns around, the sad sack of Dr. Jackman erased, replaced by the wide eyes of someone entirely new, entirely evil.

That's one of the great tricks of "Jekyll." The Hyde character isn't a monster at all. Previous incarnations accentuate the beast. Here, Hyde is presented as someone who could be Tom's brother. Aside from the gimmick of jet-black eyes (and, later, a flash of some fangs), all the makeup that went into Hyde is unnoticeable. It's part performance (Nesbitt's transition from one character to the other is outstanding) and part slight-of-hand (makeup was used to create both Jackman and Hyde, allowing for even more subtleties in the changes).

All of this is just from the first episode alone. "Jekyll" packs so much plot into each of its fifty-minute chapters that each episode feels so far removed from the events that launched the episode before it. By the final episode, the seemingly intimate scale of the first two chapters is a distant memory.

I'm reluctant to divulge too much of the plot of those later episodes, as part of the magic of "Jekyll" is in its broad twists as it builds into something quite epic. I can reveal that it's very shrewd of Moffat to open with constant mentions of "Dr. Jekyll and Mr. Hyde" as a well-known work of fiction, which places his story squarely in the real world. As such, once the plot opens up to wilder and wilder things, eventually revealing a vast, impossibly powerful network of villainy, we're more willing to accept it as part of the otherwise down-to-earth tale. Of course, we also learn that perhaps Stevenson's novel was not entirely fictional... but alas, I've said to much.

There's not a sour note in the entire series, with Moffat's scripts delicately balancing psychological thrills, biting black comedy, and honest-to-goodness frights (the final episode is exceptionally creepy), and with a cast that matches Moffat's talents word for word. (Bellman is a notable surprise, especially for those who only remember her from "Coupling.")

And then there's Nesbitt, for whom there aren't enough superlatives. His is a performance that works down to every tiny breath, every minute twitch. He makes his Dr. Jackman exciting despite the character's intentional blandness, and he makes his Mr. Hyde a most compelling creature, sinister yet sexy. Hyde is the devil himself, with all the horrors and attractions that go with it. His grin alone could put the Joker to shame.

Yet Nesbitt never makes his performance flashy in the shallow, overacting sense. It's big, sure - how could you not go big with a Hyde the way Moffat writes him? - but it's also knowingly restrained, with Nesbitt understanding that the best stuff's all in the corners, the little moments that will sink under our skin without us quite knowing it. This is one of the most carefully nuanced, perfectly complex performances to ever grace the airwaves, and every single minute of it is an absolute pleasure to watch.

This can also be said of the series itself: six episodes, 300 minutes, not a single one of them wasted. "Jekyll" is this year's finest television event.

The DVD

BBC Video brings all six episodes of "Jekyll" onto a two-disc set, three episodes per disc. The discs are packaged in a single-wide keep case with a hinged tray for the second disc.

Video & Audio

All six episodes look stunning in their anamorphic widescreen (1.78:1) transfers. There's some grain to all of the night shots, but this seems to be from the original source and not a transfer issue. Colors are deep and rich, and the darks (of which there are obviously many here) are outstanding.

The Dolby 2.0 soundtrack is equally impressive, the stereo mix being enough to handle all of the show's needs. Optional English for the Hearing Impaired subtitles are included.

Extras

Episode One features commentary by Moffat, Mackinnon (he helmed the first three episodes), and producer Elaine Cameron. Episode Six features commentary by Bellman, director Matt Lipsey (he helmed the final three episodes), and executive producer Beryl Vertue. Both commentaries are a chatty and informative delight.

"Anatomy of a Scene" (15:06, Disc One) is a detailed examination of the "lion's cage" scene. And I do mean detailed - every last bit of information regarding the shoot is covered here.

"The Tale Retold" (34:43, Disc Two) goes even further, delivering the sort of in-depth making-of stuff that puts fluffier features to shame. Cast and crew interviews are used to describe the series' history and themes. Both features are presented in anamorphic widescreen.

Previews for "Doctor Who" and "Fracture" and an ad for BBC America play as Disc One loads. Previews for "MI-5" and "Flight of the Living Dead" play as Disc Two loads. Frustratingly, you're unable to skip past or even fast-forward them.

Final Thoughts

"Jekyll" is an endlessly engaging, perfectly compact thriller, and its presentation here is equally excellent, easily belonging in the DVD Talk Collector Series.